Checking The Solenoids - Brother S-7200B Service Manual

10. CONTROL BOX AND MOTOR

10-5. Checking the solenoids

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet
before opening the face plate of the control box. Touching areas where high voltages are present can result in
severe injury.
<Machine head>
Sewing machine connector 14P
<Solenoid-type presser lifter connector>
Solenoid-type presser lifter connector 6P
55
DANGER
Control box
0743B
Thread trimmer solenoid
Thread wiper solenoid
Quick reverse solenoid
Actuator switch
Safety switch
1886M
Knee switch
Presser lifter solenoid
2331M
S-7200B
1. Disconnect the sewing machine connector 14P (1) from
the control circuit board.
2. Measure the resistance of the sewing machine connector
(1) using an ohmmeter in the x 1 range.
If the values are as shown in the table below, the
connector is normal.
Between 3–10 Thread trimming solenoid: Approx.
7.6Ω
Between 4–11 Thread wiper solenoid: Approx. 5.7Ω
Between 5–12 Quick reverse solenoid: Approx. 4.8Ω
Between 6–13 When actuator is pressed: 0Ω
When actuator is released: ∞ Ω
Between 7–14 When machine head is upright (switch
ON): 0 Ω
When machine head is tilted back
(switch OFF): ∞ Ω
1. Disconnect the solenoid-type presser lifter connector 6P
(2) from the control circuit board.
2. Measure the resistance of the solenoid-type presser lifter
connector (2) using an ohmmeter in the x 1 range.
If the values are as shown in the table below, the
connector is normal.
Between 3–6 Presser lifter solenoid: Approx. 9.6 Ω
Between 4–5 When knee switch is pressed: 0 Ω
When knee switch is released: ∞ Ω